Field of the Invention
The present invention relates to a wafer processing method of irradiating a wafer with a laser beam to divide the wafer into plural devices.
Description of the Related Art
In general, in manufacturing of devices, plural chip regions are marked out by plural streets (planned dividing lines) arranged in a lattice manner on a surface of a wafer and the devices such as integrated circuits (ICs) and large scale integrations (LSIs) are formed in these chip regions. For division of these devices, laser processing of irradiating the wafer with a laser beam along the streets on the wafer to form grooves in the wafer surface is used.
In this kind of laser processing, minute dust called debris is generated and scattered to be deposited on the surfaces of the devices when the wafer is irradiated with the laser beam, so that the quality of the devices is lowered. For this reason, a processing method has been proposed in which laser processing is carried out after a protective film is applied on a surface of a wafer in advance and debris adhering onto the protective film is cleaned and removed together with the protective film (for example, refer to Japanese Patent Laid-Open No. 2006-140311).